Implement monophyletic cluster growth checking

[ConnorChato]

Currently, monophyletic clusters have growth defaulted to 0. This function (mono.pat.cluster) is masked from the user.

[ArtPoon]

@ConnorChato is this still an issue?

[ConnorChato]

Yes. Currently I'm not entirely sure we have a super great method of resolving growth for clusters that need to be monophyletic